Railway train operating system



Dec. 17, 1935. A. a. SHAVER 2,024,664

RAILWAY TRAIN OPERATING SYSTEM Filed Sept. 2, 1933 2 Sheets-Sheet l as, r b

ANVENTOR l I ARCHIBALDG.5HAVER D 1935. A. a. SHAVER RAILWAY TRAIN OPERATING SYSTEM 2 Sheets-Sheet 2 Filed Sept. 2, 1933 4 unN 6N mu 5N INVENTDR (0 ARONIBALD GSHAvsn ATTORNEY Patented Dec. 17, 1935 UNITED STATES PATENT OFFICE 20 Claims.

This invention relates to railway train operating and dispatching systems and has special reference to the provision of improved means for communication on and with trains and between wayside stations.

The apparatus and system herein disclosed are claimed broadly in my copending applications Serial No. 227,932, filed Oct. 22, 1927; Serial No. 304,483, filed Sept. 7, 1928; Serial No. 541,131, filed May 30, 1931, and Serial No. 605,380, filed Apr. 15, 1932.

More specifically, the system disclosed provides means for communication between the conductor on the rear and the engineman on the head of trains, between trains, between trains.

and local wayside stations, between the train dispatcher and either the conductor or the engineman or both, and between the dispatcher and local wayside'stations, that information may be had by each and instructions issued with regard to the operation of the railway, including the operating of trains into and out of passing sidings in meeting and passing other trains. Further, in connection with the means for communication, there are means for the operation of the switches concerned for trains to enter and leave sidings and pass other trains. In. these systems each trai'n operates in a communication zone of its own which always includes an intermediate wayside circuit. The stretch of track over which the trains operate is sectionalized into blocks and an intermediate circuit is provided for each block; but as, and during the interval in which the train travels from one block to the next, the two intermediate circuits for the adjoining blocks are automatically connected together as one circuit, thus creating a traveling circuit effect, which, for convenience, is sometimes referred to as a traveling intermediate circuit. The intermediate circuits are arranged so that there is always an intermediate circuit in continuous communicative relation with both ends of the train as the train travels through the correspondng blockor blocks and each such circuit is also provided with means for communicative connection with the communication means provided for the dispatcher and the local wayside stations.

The means used for communication between rear end and head end of a train about to pass into, through or to leave a passing siding territory, are automatically connected with the dispatchers communicating set, but the dispatcher may cancel such connection. Means are also provided for persons in local wayside Stations to normally communicate with standing and mov-- ing trains within prescribed areas. The means referred to are under the control of the dispatcher to the extent that he may, at will, connect or disconnect the communication circuit .5 connected with his communication set from any train or local wayside communication set.

One object of the invention is the provision of means for continuous communication between two communication stations on a train while 10 the train is passing between the main line track and the passing siding track, of a passing siding location, and yet, under normal conditions, communications passed between the two train stations, while the train is on the passing siding track, are kept to the train.

Another object of the invention is the provision of means whereby, when desired, communication may be carried on between two points on the train, while the train is on the passing siding, and yet, the train is normally not in communicating relation with another train on the main track adjoining the passing siding track. v 1 Another object of the invention is the provision of means for establishing communication be- .5 tween a train on a siding track and a train on an adjoining main track.

Still another object of the invention is the provision of means for increasing the efiiciency of the system in the transfer of communication energy between the train and the wayside and between two points on a train.

Provision is made for communication to be carried on between two communication stations, as two localroadside stations, simultaneously with communication being carried on between two or more stations, as between a train carried station and the dispatcher, neither set of communications interfering with the other. 40

Provision is also made for carrying on communication between two stations in the system with the transmitter and receiver units of the communication set in each of the stations connected into the transmission organization at the same time.

To the accomplishment of the foregoing and such other objects as may hereinafter appear, my invention consists in the elements and their relation one to the other, as hereinafter particularly described and defined in the claims, reference being had to the accompanying drawings which show a preferred embodiment of my invention, and in which:-

Fig. 1 is a diagrammatic view of a portion of 56 a line illustrating the wayside features of the communication system.

Fig. 2 is an extension of Fig. 1.

Fig. 3 is a diagrammatic view of a portion of a railway line illustrating an arrangement of wayside apparatus and circuits which are a modiflcation of those disclosed in Figs. 1 and 2.

Fig. 4 is a schematic showing of the method 01 operation of relays Oi, 02, etc.

Fig. 5 is a schematic diagram illustrative of a train operated mechanical circuit closing device.

Fig. 6 is an elevation of a cross section of a railway track illustrating the relative arrangement of running rails and conductor on the wayside with the coils or inductors carried on the train.

Fig. 'l is a plan view, schematically showing the arrangement of communication sets on the locomotive and caboose of a train, with reference to the running rails and conductor.

Fig. 8 is a schematic diagram of the wiring and apparatus comprising a communication set.

Fig. 9 is a schematic diagram of a modification oi the communication set similar to that shown in Fig. 8.

Fig. 10 is a cross sectional view showing the arrangement of the coils or inductors for a local wayside station with reference to the intermediate circuit.

Figs. 1 and 2 are intended to be joined together with the right hand end of Fig. 1 connected to the left hand end of Fig. 2 to illustrate the circuit organization and the general arrangement of the system, typical of that for the usual railroad.

Fig. 3, which illustrates a somewhat difierent arrangement of wayside circuits at passing siding locations, may be considered as a continuation of Figs. 1 and 2, as hereinafter explained, or it may be considered as a passing siding organization optional with that shown in Figs. 1 and 2.

In the Figs. 1, 2, and 3, Al and A2 are the track rails upon which the trains operate. BX represents batteries for track circuits. The insulated joints are illustrated by a short straight line across the heavy line representing the track rails and are generally designated by Jl. The condensers connecting the conductors of the intermediate circuits to the track rails are generally designated Kl. The condensers which are connected around certain insulated joints are generally designated K2. The track switches are designated S followed by a sufiix. The track switches may be operated by means designated by R followed by a suffix which agrees with that for the associated track switch. The track circuit relays are designated T folowed by a suflix. Selectors are designated by L followed by a suflix. Relays co-operating with selectors and known as of! and on relays are designated by followed by a number which is the same as that for the selector with which used. Relays for automatically connecting intermediate circuit to the dispatcher's communicating circuit are operated in a stick circuit and designated as N relays followed by a suillx. Fixed transpositions o! the conductors in the intermediate circuits of the passing siding locations XI and X2 are generally designated T with a numeral suffix. The inductors or coils for inductively connecting the wayside communication set at local stations and the communication sets on the trains with the intermediate circuit are generally designated U with a numeral suffix. The passing siding track are generally designated PS and the main lines ML. Ql, Q2, Q3 and Q represent local wayside communication stations and Q4 the dispatchers communication stations. The batteries for wayside circuits, other than track circuit batteries, 5 are designated B with a numerical sufiix. Circuit closing push keys are designated by the letter P with a numeral sufilx.

Figs. 1 and 2 together, and Fig. 3 together with Figs. 1 and 2, or separately, show a stretch of railroad representative of a single track line with passing sidings, comprised in a dispatchers district, upon which trains operate in both directions and within which trains meet and pass each other. The general arrangement of the wayside circuits and features of the communicating system is illustrated in these figures.

The railroad is divided into sections or blocks A, B, C, D, E, etc. A and Q are shown in Fig. 1 and 3 respectively, as only partial blocks or secac tions. If A and Q were complete, A would be like block or section G and Q would be similar to section E in arrangement. EF-G is a stretch of single track between the two passing siding locations XI and X2 and K to M is the stretch of single track between passing siding locations X2 and X3. The switch operating devises B may be either manually or power operated or some of them may be manually operated and some power operated.

Track circuits are shown where required to operate the various circuits of the communication system as will hereinafter be pointed out. The communication system of my invention is readily operable on a railway line where continuous track circuiting is required for other purposes in which case existing track circuits are used and modified as necessary to serve the communication system, but without interfering with the operation of block signals. or any other similar railway device, which are track circuit controlled. Two forms of track circuits are shown in Fig. 1. The track circuit generally used is well known in the art and comprises a stretch of track with a battery at one end connecting the two rails and a relay at the other end connecting the same two rails. This provides a closed circuit through which electrical energy is flowing at all times. Such circuits are illustrated, for example, in sections B, D, and E. At section F another form of track circuit is illustrated and may be used to advantage, particularly on a railway line not already equipped with track circuits for other purposes. It will be observed that this latter is a normally open track circuit. The 5 relay TF, in series with the battery BX, is connected across the two rails Al and A2 of a short stretch of track. The length 01 this stretch need be only to ft., just long enough to insure that there will always be a pair of wheels 30 in the section when a train is passing. Current flows in such a track circuit to operate the relay TF to close its front contacts, only when the section of rails is occupied by a train. The use of such a track circuit results in a saving of elec- 5 trical energy as compared with the normally closed track circuit where electrical energy is consumed all the time.

Wayside communication or intermediate circuits are provided for the transmission of the communication currents. These are arranged in a manner to best suit local and trafiic conditions; for example, at passing siding location XI, the intermediate circuit normally corresponds to the stretch comprising sections B, C and D. For 7 the stretch comprising sections EF, one intermediate circuit is provided. For the block G another intermediate circuit is provided, etc.

As illustrated in Fig. 3, the intermediate cir"- cuit arrangement for the main line outside of passing siding locations, is similar to that described for Figs. 1 and 2; but at passing siding locations, as X3, two intermediate circuits are provided, one for the passing siding track and the other for the main line track. The intermediate circuit for the main line is associated with the stretch comprising sections N, O, and P, while that for the siding normally corresponds to the stretch comprising only a portion of sections N and P and all of section 0.

The intermediate circuits illustrated are of two forms, one, such as that for stretch B-C-D, comprising a conductor placed on the ties in the center of both the main track and the passing siding track, makes one complete loop and normally closed circuit associated with both tracks. The other type is that illustrated for stretch E-F, for example, where the conductor, as one side of the intermediate circuit, is located on the ties in the center of the track and the track rails, connected in parallel, act as the other side of the circuit forming a complete loop or normally closed circuit.

For some or all of the passing siding locations, depending upon conditions local to the railroad, I may use the arrangement illustrated for passing siding location X3 of Fig. 3, in which the track rails are used as one side of the intermediate circuit for both the passing siding track and the main track and a conductor connected through condensers to the track rails at both ends of the block for each track, and carried on the ties in the center of the track, forms the other side of the intermediate circuit for each track. This provides one intermediate circuit for the main track and another intermediate circuit for the passing siding track, each electrically isolated from the other.

I have referred to the conductor, which forms one side of the intermediate circuit, as being located on the ties in the center of the track. I prefer this location since practically on all railroad tracks trains are operated at times forward or backward and facing in either direction. Therefore, for such operation the train carried equipment, without any change over arrangement, always co-operates with the wayside equipment. It is obvious, however, that the con-' ductor may be located elsewhere than on the ties in the center of the track. It may be placed on the ends of the ties, but in such case there would need to be a train carried co-operating inductor or coil provided for each side of the train, and generally, a circuit switch adapted to select as between the two inductors for efficient operation.

That station agents, yardmasters and other employes who may be stationed along the railroad may communicate with each other and with trains and, when necessary, with the dispatcher, local communication stations Q1, Q2, Q3, and Q5 are provided. When a train approaches a passing siding location, it automatically operates devices to connect the intermediate circuit for the portion of railway line or block, which includes the passing track, with the dispatchers communicating circuit, conductors DI and D2. The same devices which the train automatically operates may also be operated through the circuit closing push keys P, at the local wayside stations QI, Q2, and Q5 for connecting the intermediate circuit for the block with the dispatchers communicating circuit, conductors DI and D2. The local station Q3, as shown, is not provided with means for initiatingcommunication with the dispatcher. 5 Q4 represent the dispatchers communicating station and includes transmitting and receiving communication devices as well as selective equipment for operating relays at remote points as will be hereinafter explained.

Each of the relays O, which are at remote points, is controlled by the associated selector L of the same suflix, and may be of the form shown in Fig. 4. These relays have two positions. Referring to Fig. 4, when the electromagnet of relay TI I, for example, is energized, armature IDI is raised, causing the ratchet wheel RW to turn. Since this ratchet wheel is on the same shaft with cam CM, the cam will be operated to make a quarter turn from the position shown and the fingers 23', I2, and I8 will open their front contacts and close their back contacts. When electromagnet TII is again energized, armature IIII is again operated, turning ratchet wheel RW another quarter of a turn, 25 which causes the cam GM to assume the upright position as shown so that contact fingers 23, I2, and I8 are again closed on their front contacts, etc.

Description of circuits In order to avoid unnecessary repetition and .to simplify the description of the system as much as possible, I will now describe a number of representative circuits as they exist under various 7 conditions arising during the practical operation of the system. These circuits are given identifying designations for convenience in referring to them in the description of the operation which follows. The first group of circuits taken up are those for the track sections shown in Figs. 1 and 2. The intermediate circuit and various controlling circuits for each track section are described in order beginning with the circuits for track section A. Following the description of the circuits shown in Figs. 1 and 2, I will describe the corresponding circuits shown in Fig. 3.

The circuits for Figs. 1 and 2 are as follows:

INTERMEDIATE CIRCUITS (BLocK A AND Srnarcn B-C-D) Circuit #1 (Normal intermediate circuit for block including section A and main line to the left thereof) This intermediate circuit normally includes conductor I, front contact 2, conductor 3, condensers KI and the two track rails AI and A2 in parallel. The left hand end of this circuit which is not shown, will be exactly the same as the left end of thecircuit shown for section G.

Circuit #2 (normal intermediate circuit for passing siding location XI, stretch BC-'--D) The intermediate circuit for passing siding location XI, which comprises the stretch BC-D, normally includes conductor 4, conductor 5 in the center of the passing siding track, transposition TI, conductor 5 in the center of the main line track, front contact'fi, con- .ductor I in the center of the passing siding track, transposition TI, conductor I in the center of the main line track, front contact 8, conductor 9, back contact I0, conductor II and back contact I2. 75,

Circuit #Za (intermediate circuit for passing siding location X1 when relay O1 is energized) This circuit is the same as Circuit #2 except that the winding 0 of transformer MI is included therein due to the closure of front contact l2.

Circuit #Zb (intermediate circuit for passing siding location X1, stretch BCD, when relay N1 is energized) This intermediate circuit comprises coil a of transformer MI, front contact ll, conductor l3, conductor 5 in the center of the siding track, transposition Tl, conductor 5 in the center of the main line track, front contact 6, conductor I in the center of the passing siding track, transposition Tl, conductor I in the center of the main line track, front contact 8 and conductors 9 and I5. When front contact I is closed, back contact l8 must be open.

Circuit #3 (combined intermediate circuit for block A and stretch BCD when relay TA is de-energized) Circuit #3a (combined intermediate circuit for block A and stretch BCD when connected with dispatchers communicating circuit, by the energization of relay 01) This is the same as Circuit #3, excepting coil 0 of transformer M l is inserted in the circuit.

Circuit #3b (combined intermediate circuit for block A and stretch B-CD when connected with dispatchers communicating circuit, by the energization of relay N1) This is thesame as Circuit #3, excepting contact I8 is open and coil a of transformer MI, is connected by conductor I! with conductor 3 and by front contact I4 and conductor l3 with conductor 5.

Gon'rnoLun'o moons Circuit #4 (circuit for controlling relay N1 by relays TA and TB) With relays TA and TB de-energized, back contacts 26 and 21 are closed and a circuit is completed for relay NI from battery Bl, conductor 22, contact 23 closed on either its front point or its back point, conductor 24, electromagnei; coil N I, conductor 25, back contact 28, back contact 21 and conductors 28 and 29. This circuit causes relay N| to become energized to close its front contacts 3|a, l4, and 2| and open its back contact I8.

Circuit #4:: (circuit for controlling relay N1 by push keys P1 and P2) This circuit is the same as Circuit #4, except that it is completed through the contacts of push keys Pl or P2 instead of through contacts of relays TA, TB, TD and TE.

Circuit #4b (circuit for controlling relay N1 by relays TD and TE) 5 Circuit #4c (circuit for controlling relay N1 by push key P3) Since contact of push key P3 is in parallel with contacts 3| and 32, the closing circuit for 9 relay N is the same as Circuit #4b, except the contact of push key P3 takes the place of contacts 3| and 32.

Circuit #4d (stick circuit for relay N1) When relay NI is energized over any one of 25 Circuits #4, #4a, #4b or #4c, it closes front contact 3|a, thereby establishing itself energized in a circuit comprising battery Bl, conductor 22, contact 23 made on either its front or back 30 point, conductor 24, electromagnet coil N l, conductor 38a, front contact 3|a, conductors 32a, 28, and 29.

Circuit #5 (energizing, 0/ "017 and on" relay O1) 0 When contact 35 is closed, relay 0| is energized to an abnormal condition in a circuit comprising battery Bl, conductors 22 and 31, electromagnet ccil 0|, conductor 36, contact 35 closed and conductors 34 and 29. The contact 40 35 is usually closed for only a short interval of time. Therefore, it is necessary that relay 0| be arranged to hold its contacts closed in the position to which operated until the electromagnet coil Ol is again energized, due to contact 35 45 again being closed, when the contacts are shifted to their other position. A relay of this character is illustrated in Fig. 4 and elsewhere described.

Circuit #6 (operation of selector L1) 50 When the dispatchers selective equipment DSE disclosed in Fig. 8, is operated, coded impulses of current flow over the dispatchers communicating circuit, conductors DI and D2, and conductors 28, I3, I8, and 33 to selector coil Ll, 55 which responds to close the contact 35 in a manner hereinafter referred to.

Circuit #7 (connecting primary b of transformer M1 to dispatcher's circuit by relay O1) 0 When front contact l8 of relay 0| is closed, the primary coil b of transformer MI is connected with conductors DI and D2 through the circuit comprising conductors 28 and I9, front 65 contact l8 closed, coil b and conductor I8.

Circuit #7a (connecting primary b of transformer M1 to dispatchers circuit by relay N1) When contact 2| of relay N is closed on its 70 front point, a circuit is established connecting primary b of transformer Ml to the dispatchers line, conductors DI and D2, said circuit comprising conductor 28, front contact 2| closed, coil b of transformer MI and conductor I8. 75

INTERMEDIATE cmcmrs (Srnsrcnms BC-D AND E-F AND BLOCK G) Circuit #8 (normal intermediate circuit for stretch E-F) Circuit #8a (intermediate circuit for stretch E-F with relay O2 energized) This circuit is the same as Circuit #8, except that when front contact 38 is closed, coil of transformer M2 is included in the intermediate circuit.

Circuit #9 (combined intermediate circuit for stretches B-C'-D and E-F with relay TE de-energized) When contacts 42 and 8 are closed on their back points, conductor 43 is connected through back contact 8 with conductor 1 and conductor 4| is connected through back contact 42 with conductor 9, thus forming one enlarged or combined circuit for the stretches B'CD and E-F. The connection of the adjacent circuits in this manner produces the effect of a transposition as conductor 1 which lies between the rails of the main line track of block D is connected via contact 8 and conductor 43 to the rails of block E and conductor 4| which lies between the track rails of block E is connected via contacts 42, conductor 9, contacts I0, conductor contacts l2, and conductor 4 to conductor which lies between the rails of the siding of block D.

Circuit #9a (combined intermediate circuit for stretches B--C,D and E-F connected with dispatchers circuit by relay 01) This is the same as Circuit #9, excepting coil c of transformer MI is inserted in the circuit by the closure of front contact l2.

Circuit #9b (combined intermediate circuit for stretches B--CD and E-F connected with dispatchers circuit by relay N1 This is the same as Circuit #9, except coil a of transformer MI is connected by conductor IS with conductor 9 and by front contact l4 and conductor l3 with conductor 5.

Circuit #90 (combined intermediate circuitfor stretches B-C-D and E-F connected with dispatchers circuit, by relay 02) This is the same as Circuit #9, excepting coil 0 of transformer M2 is inserted in the circuit by the closure of front contact 38.

Circuit #10 (normal intermediate circuit for the block G) Circuit #10a (intermediate circuit for block G with relay O2 energized) The intermediate circuit for block G remains the same as Circuit #10 excepting that it now includes coil a of transformer M2.

Circuit #11 (combined intermediate circuit for stretch E-F and block G with relay TF energized) With relay TF energized, contacts 54, 40, and 10 5| are closed on their front points, conductor 4! is connected to conductor 53, and conductor 55 is connected to conductor 39, thus forming one combined or enlarged intermediate circuit for the stretch EF and block G, and transposing 15 the conductors in relation to each other.

circuit, by relay 02) This is the same as Circuit #11, except coil c r of transformer M2 is inserted in the circuit by the closure of front contact 38. Coil a of transformer M2 is also inserted in the circuit by the closure of front contact 52; but when contact 5| is closed on its front point, conductor 4| is connected through conductor 50 with conductor 56a, thus forming a parallel path with the conductors connected through front contacts 54 and 52 so that the coil a of transformer M2 is shunted. The function of this arrangement is to maintain but one transformer secondary in the combined intermediate circuit for stretch E-F and block G when connection is made with the dispatchers communication circuit conductors DI and D2.

CONTROLLING CIRCUITS When contact 35a of selector L2 is closed, relay O2 is energized to an abnormal condition in a circuit comprising battery B2, contact 35a, conductor 36a, electromagnet coil 02 and conductor 31a. Explanation of operation of these off and on relays is referred to under Circuit #5 and the construction is. shown in Fig. 4.

Circuit #13 (operation of selector L2) When the dispatchers selective equipment, as DSE, shown in Fig. 8 is operated, coded electric current impulses flow over conductors DI and D2 and 49 and 48 to selector coil L2, thus energizing this coil to close contact 35a as will later be explained.

relay 0 Circuit #14 (Primary b of transformer M2 connected to the dispatchers circuit, by relay 02) When contact 46 of relay O2 is closed on its front point, primary 0 of transformer M2 is connected to the dispatchers line, i.e., conductors DI and D2, through conductor 45, coil b of transformer M2, front contact 46 and conductors 41 and 4s.

INTERMEDIATE CIRCUITS (BLOCK G AND srnn'rcn I H-I-J) Circuit #15 (normal intermediate circuit for passing siding location X2, stretch H-I-J) The intermediate circuit for passing siding location X2 which includes the stretch H-I-J, normally includes conductor 58, conductor 58 in the center of the passing siding track, transposi- 'tion T2, conductor 59 in the center of the main line track, front contact 68, conductor 6| in the center of the passing siding track, transposition T2, conductor 6| in the center of the main line track, front contact 62, conductor 83, back contact 54, conductor 65 and back contact 66.

Circuit #15a (intermediate circuit for passing siding location X2, stretch H-I-J, with relay O3 energized) This intermediate circuit is the same as intermediate Circuit #15 except that it includes secondary coil 0 of transformer M3.

Circuit #16 (intermediate circuit for passing siding location X2, stretch HI--J, with relay N2 energized) This is the same as Circuit #15, except coil a of transformer M3 is connected in the circuit by conductor 69 and front contact 68 and conductor 61. Contact 64 which is in parallel with contact 88, is open.

Circuit #17 (combined intermediate circuit for block G and stretch H-I-J, with relay TG rte-energized) With relay TG de-energized, contacts 56 and 80 are made on their back points, conductor 55 is connected to conductor GI, and the track rails Al and A2 for block G are connected via conductor 51 and back contact 60 with conductor 59, thus forming one combined or enlarged intermediate circuit for the block G and stretch HIJ.

Circuit #17a (combined intermediate circuit for block G and stretch H-IJ connected with dispatchers circuit by relay 03) This is the same as Circuit #17, excepting coil 0 of transformer M3 is inserted in the circuit.

Circuit #17b (combined intermediate circuit for block G and stretch H-I-J connected with dispatchers circuit by relay N2) I'his is the same circuit as #17, excepting contact 64 is open, and coil a of transformer M3 is connected by conductor 69 with conductor 83 and by front contact 68 and conductor 61 with conductor 59.

Circuit #17c (combined intermediate circuit for block G and stretch HI--J connected with dispatchers circuit by relay 02) This is the same as Circuit #17, excepting back contact 52 is opened and front contact 52 is closed, inserting coil a of transformer M2 in the circuit.

CONTROLLING oracoirs Circuit #18 (circuit for controlling relay N2 by relays TG and TH) Circuit #18a (circuit for controlling relay N2 by push keys P4 and P5) The contact keys P4 and P5 are in parallel with each other and with contacts 80 and 8| and either push key contact may replace contacts 80 and 8| in Circuit #18.

Circuit #18!) (circuit for controlling relay N2 by relays TJ and TK) Circuit #180 (circuit for controlling relay N2 by push key P6) Contact of push key P8 replaces contacts 0 and 86 in Circuit #18b.

Circuit #19 (stick circuit for relay N2) When relay N2 is energized in the Circuits #18, #18a, #18b or #l8c, it closes front contacts 85a, thereby maintaining itself energized in a circuit comprising battery B3, conductor 16, contact 11 made on either its front or back point, conductor 18, elec romagnet coil N2, conductor 84a, front contact 85a and conductors 86a, 82, and 83.

Circuit #20 (energizing of "017 and on relay 03) When contact 89 of selector L3 is closed, relay O3 is energized to an abnormal condition in a circuit comprising battery B3, conductors 16 and 9|, electromagnet coil 03, conductor 90, contact 89 closed and conductors 8B and 83. The contact 89 is usually closed for only a short interval of time. Therefore, it is necessary that relay 03 be arranged to hold its contacts closed in the position to which operated until the electro magnet coil 03 is again energized, due to contact 89 again being closed when the contacts are shifted to their other position. A relay of this character is illustrated in Fig. 4 and elsewhere described.

Circuit #21 (operation of selector L3) When the dispatchers selective equipment DSE shown in Fig. 8 is operated, coded impulses of current flow over the dispatchers communicating circuit, conductors DI and D2 and conductors 10, 81, I4, and 13 to selector coil L3 which responds to close the contact 89, as will be later described.

Circuit #22 (connecting primary b of transformer M3 to dispatchers circuit by relay 03) When front contact 12 is closed, the primary coil b of transformer M3 is connected with conductors DI and D2 through the circuit comprising conductors l4 and 13, front contact 72 closed, coil b and conductor 18.

Circuit #23 (similar to Circuit #22 but when 6 contact 75 is closed) When contact 15 is closed on its front point a circuit is established, connecting primary b of transformer M3 to dispatchers line, i. e., con- 6 ductors DI and D2, said circuits comprising conductor 14, front contact 15 closed, coil b and conductor 10.

INTERMEDIATE cnzcurrs (sranron BLOCK K) Circuit #24 (normal intermediate circuit for block K) This intermediate circuit normally includes the track rails Al and A2 in parallel, condensers l5 K2 around insulated joints, condensers KI, conductor 92, front contact 93 and conductor 94 in the center of the main track between the rails AI and A2. The right hand end of this circuit which is not shown will be similar to the right end of the circuit shown for stretch E-F. Normally, this circuit is closed.

Circuit #24a (combined intermediate circuit for stretch H-I-J and block K with relay TK de-energized) When contacts 93 and 62 are made on their back points, as when there is a train in the track circuit for relay TK, conductor 94 is connected to conductor 63, and conductor 6| is connected to conductor 92 and the track rails AI and A2 for block K, thus forming one combined or enlarged intermediate circuit for the stretch HIJ and block K.

The circuits for Fig. 3 are as follows:

INTERMEDIATE CIRCUITS (BLOCK M AND STRETCH NOP) Circuit #25 (normal circuit for block M) This intermediate circuit normally includes conductor I8I, front contact I82, conductor I83, condensers KI and the two track rails AI and A2 in parallel and including any condensers K2 which there may be around insulated joints in the track rails. The left hand end of this circuit is not shown, but is the same as the left hand end of the circuit illustrated for block G. Normally, this circuit is closed. If Fig. 3 is made a continuation of Fig. 2, there would need to be an interveningsection L, like F with its track relay TF, off and on relay O2, transformer M2 and selector L2, between the blocks K and M. This would provide for communication between trains and the dispatcher.

Circuit #26 (normal intermediate circuit for main line at passing siding location X3, stretch NOP) The intermediate circuit for passing siding location X3, which includes the, track sections N, O, and P, normally includes conductors I02 and I03, condensers KI, main line track rails AI and A2 in parallel, condensers K2 as required, around insulated joints in the track rails, condensers KI at the left hand end of section N, conductor I04, front contact I05, conductor I05, contact I01, closed when switch S5 is normal, conductor I08 located in the center of the main track, contact I09 closed when switch S6 is normal, conductor IIO, front contact III, conductor II2, back contact II3, conductor H4 and back contact II5.

Circuit #26a (intermediate circuit for main line at passing siding location X3 with relay O5 energized) This is the same as Circuit #26 above described, excepting that secondary c of transformer M5 is now inserted in the circuit.

Circuit #2617 (intermediate circuit for main line at passing siding location X3 with relay N4 energized) When contact I54 is closed, back contact II3 must be opened. This circuit is the same as Circuit #26, excepting that the secondary a of transformer M5 is inserted in the circuit through conductors I55 and I 53.

Circuit #27 (normal intermediate circuit for passing siding PS at location X3) Circuit #27a (circuit for passing siding PS at location X3 with relay O4 energized) This is the same as Circuit #27 above described, excepting that secondary a of transformer M4 is now inserted in the circuit.

Circuit #27b (intermediate circuit for passing siding PS at location X3 with relay N3 energized) With relay N3 energized, front contact I63 is closed and back contact I23 must be opened. This circuit is the same as Circuit #27, excepting that secondary c of transformer M4 is inserted in the circuit through closed contact I63 and conductors I62 and I65.

Circuit #28 (intermediate circuit at passing siding location X3 when track: switch S5 is reversed) When track switch S5 is reversed, the intermediate circuit comprises track rails AI and A2 in parallel, condensers K2 around insulated joints in these track rails, condensers KI, conductor I04, front contact I05, conductor I06, contact I2! now closed since switch S5 is reversed, conductor I I9, condensers KI, track rails AI and A2 in parallel, condensers K2 around insulated joints in these track rails, condensers KI at the right hand end of the siding track, contact I20 closed as the switch S5 is normal, conductor I2I, conductor I22 in the center of the passing siding track, back contact I23, conductor I24, back contact I25, conductor IIB, conductor H1 in the center of passing siding track, contact I26 closed since switch S5 is reversed, conductor I08 in the center of main line track, contact I09 closed as switch S6 is normal, conductor IIO, front contact III, conductor II2, back contact II3, conductor II4, back contact II5, conductors I02 and I03, condensers KI and track rails AI and A2 at the right hand end of section P. It will be observed that under conditions where track switch S5 is reversed, the two intermediate or loop circuits, one for the passing siding PS, the other for the main line ML, are now connected in series as one circuit.

Circuit #28a (intermediate circuit at passing siding location X3 when track switch S5 is reversed and relay N4 is energized) This is the same circuit as #28 except coil a of transformer M5 is inserted in the circuit when contact I54 is closed, and coil b is connected to the conductors DI and D2 through front con- 7 tact I56.

This is the same circuit as #28 except coil 0 of transformer M4 is inserted in the circuit when front contact I63 is closed and coil b is connected to the conductors DI and D2 through front contact I66.

Circuit #28c (intermediate circuit at passing siding location X3 when track switch S5 is reversed and relays N3 and N4 are energized) This is the same as Circuit #28a, except coil c of transformer M4 is also inserted in the circuit when front contact I63 is closed, and coil b is connected to the conductors DI and D2 through front contact I66. It will be noted that this intermediate circuit is a combination in series of intermediate Circuits #26b and #2'1b.

Circuit #29 (intermediate circuit at passing siding location X3 when switch S6 is reversed) This circuit is similar to Circuit #28, excepting that in this case, switch S6 is reversed and switch S5 is normal. With switch S6 reversed, contacts I20 and I09 are opened and contacts I21 and I28 are closed. The intermediate or loop circuits for the passing siding track and the main line track, both in the stretch N--OP at the location X3, are now connected together in series as one circuit, comprising, track rails AI and A2 in parallel, condensers K2 around insulated joints, condensers KI, conductor I04, front contact I05, conductor I06, contact I01, conductor I08 in the center of the main line track, contact I21 closed as track switch S6 is reversed, conductor I2I, conductor I22 in center of siding track, back contact I23, conductor I24, back contact I25, conductor II6, conductor H1 in center of siding track, contact II8, conductor II9, condensers KI, siding track rails AI and A2, condensers K2 around insulated joints in siding track rails, condensers KI, contact I28 closed as switch S5 is reversed, conductor IIO, front contact III, conductor II2, back contact II3, conductor II4, back contact II5, conductors I02 and I03 and condensers KI, connected to track rails AI and A2 at right end of stretch NOP.

Circuit #29a (intermediate circuit at passing siding location X3 when track switch S6 is reversed and relay N4 is energized) This circuit is the same as #29, except the coil a of transformer M5 is inserted in the circuit when contact I54 is closed and coil b is connected to the conductors DI and D2 through front contact I56.

Circuit #29b (intermediate circuit at passing siding location X3 when track switch S6 is reversed and relay N3 is energized) This is the same circuit as #29, except coil 0 of transformer M4 is inserted in the circuit when front contact I63 is closed, and coil b is connected to the conductors DI and D2 through front contact I66.

Circuit #29c (intermediate circuit at passing siding location X3 when track switch S6 is reversed and relays N3 and N4 are energized) This is the same as Circuit #29a, exceptcoil c of transformer M4 is also inserted in the circuit and coil b is connected to the conductors DI and D2 through front contact I66. It will be noted that this intermediate circuit is a combination in series of intermediate Circuits #26b and #2717.

Circuit #29 (A and B)-(intermediate circuit arrangement at location X3 when passing siding switchcs S5 and S6 are both reversed) Under this condition, two intermediate circuits exist in parallel for the main line track and the siding track at location X3:

(A) This intermediate circuit comprises conductor II6, conductor H1 in the center of passing siding track, contact I26 closed since switch S5 is reversed, conductor I08 in the center of main line track, contact I21 closed since switch S6 is reversed, conductor I2I, conductor I22 in the center of passing siding track, contact I23, conductor I24 and contact I25.

With contact I25 closed on its front point, secondary a of transformer M4 is connected into the intermediate circuit just described and with contact I69 closed on its front point, primary coil b of transformer M4 is connected to conductors DI and D2 of the dispatchers communicating circuit.

With contacts I63 and I66 closed on their front points, secondary c of transformer M4 is inserted in this intermediate circuit and primary b of transformer M4 is connected to conductors DI and D2 of the dispatchers communicating circuit.

With contacts I02 and I05 made on their back points with switches S5 and S6 both reversed, intermediate Circuit #29A does not form a part of the combined intermediate circuit for block M and stretch N-O-P.

With contacts I and III closed on their back points, intermediate Circuit #29A does not form a part of the combined intermediate circuit for stretch N-0P and block Q.

(B) This intermediate circuit comprises main track rails AI and A2 in parallel including the condensers K2 around insulated joints, condensers KI, conductor I04, front contact I05, conductor I06, contact I21 closed since switch S5 is reversed, conductor II9, condensers KI, the two track rails AI and A2, condensers KI at the right hand end of the passing siding at location X3, contact I28 closed since switch S6 is reversed, conductor H0, front contact III, conductor II2, back contact II3, conductor II4, back contact II5, conductors I02 and I03, condensers KI at the right hand end of section P and track rails AI and A2.

With contact II5 closed on its front point, secondary c of transformer M5 is inserted in the intermediate circuit. When contact I I5 is closed on its front point, contact I59 must also be closed on its front point, thus connecting primary b of transformer M5 to conductors DI and D2 of the dispatchers communicating circuit.

With front contacts I54 and I56 closed, secondary a of transformer M5 is inserted in this intermediate circuit and primary b of transformer M5 is connected to the conductors DI and Circuit #30 (intermediate circuits for block M and for main line track of stretch NOP combined as one circuit) When contacts I82 and I05 of relay T5 are made on their back points, conductor I8I is connected through conductor I04 to the track rails AI and A2 of section N and the track rails for section M are connected through conductor I83 and back contact I05 with conductor I06, thus forming one combined or enlarged inter mediate circuit comprising the block M and stretch N-OP. If the switch S5 is normal, this combined intermediate circuit exists for the main line track only.

Circuit #30a (intermediate circuit for block M and for passing siding track PS of stretch N-OP combined as one circuit when switch S5 is reversed) When contacts I82 and I05 of relay T5 are made on their back points, conductor I8I is connected through conductor I04 with the track rails AI and A2 of section N and the track rails for section M are connected through conductor I83 with conductor I08. With switch S5 reversed, contacts H8 and I01 are opened and contacts I28 and I21 closed; hence, conductor I06 is connected via contact I21 with the track rails AI and A2 of the passing siding track and conductor H1 is connected via contact I28 with conductor I08. Therefore, this combined intermediate circuit includes the intermediate circuit for the main line track ML connected in series with the intermediate circuit for the passing siding track PS.

Circuit #30!) (intermediate circuit for block M and for passing siding track of stretch N-O-P combined as one circuit when switch S6 is reversed) When contact I82 and I05 are made on their back points, conductor I8I is connected through conductor I04 with the track rails AI and A2 of section N and the track rails for section M are connected through conductor I83 with conductor I06. With switch S8 reversed, contacts I20 and I09 are opened and contacts I21 and I28 are closed, hence, conductor H is connected via contact I28 with the track rails AI and A2 of the passing siding track and conductor I08 is connected via contact I21 with conductor I22. Therefore, this combined intermediate circuit includes the intermediate circuit for the main line ML connected in series with the intermediate circuit for the passing siding PS.

Circuit #300 (intermediate circuit for block M and for passing siding track of stretch NO-P combined as one circuit when both switches S and S6 are reversed) When contacts I82 and I05 of relay T5 are made on their back points, conductor I8I is connected through conductor I04 with the track rails AI and A2 of section N and the track rails for section M are connected through conductor I83 with conductor I06. With switch S5 reversed, contacts H8 and I01 are opened and contacts I26 and I21 are closed; hence, conductor I06 is connected via contact I21 with conductor H8 and the track rails AI and A2 and conductor H1 is connected via contact I26 with conductor I08. With switch S6 reversed, contacts I20 and I08 are opened and. contacts I21 and I28 are closed: hence. conductor I08 is connected via contact I21 with conductor I22. Therefore. this combined intermediate circuit includes the parallel connected track rails AI and A2 of the main line in series with the paralcircuit through its contact I31.

lel connected track rails AI and A2 of the passing siding. The center of track conductors of both the main line and the passing siding are connected together to form a closed intermediate circuit, for both the main line and the passing 5 siding of the stretch N--O-P, which is in no way connected in the combined intermediate circuit for the block M and stretch NO-P when contacts I 82 and I05 are closed on their back points.

CONTROLLING Cmcm'rs Circuit #31 (circuit for controlling relay N4 by relay T6) When back contact I30 is closed, this circuit comprises battery B5, conductor I34, contact I33 made on either its front or back point, conductor I32, electromagnet coil N4, conductor I3I, back contact I30 and conductors I29, I35 and I15. The closing of this circuit energizes relay N4 closing its front contacts I31, I54 and I55 and opening its back contact II3. Front contact I31 completes a stick circuit for relay N4 comprising battery B5, conductor I34, contact I33 35 made in either position, conductor I32, electro magnet coil N4, front contact I31, and conductors I38, I36 and I15. Since the push key P1 is in parallel with back contact I30, the operation of this key to close its contact will also result in relay N4 being energized and stuck in a The push key P1 may be located near one of the track switches S5 or S6 or at a point convenient for trains to stop or in a wayside station or there may be several of these push keys in parallel arrangement at each of the various locations named. Back contact I39, which is also arranged in parallel with contact I 30, when closed, will cause energization of relay N4 as heretofore explained, with the result that relay N4 will remain energized in a circuit created through its front contact I 31, as also heretofore explained.

Circuit #32 (circuit for controlling relay N3 by 5 relay T7) When back contact I of relay T1 is closed, relay N3 is energized in a circuit comprising battery B4, conductor I48, contact I made on either its front or back point, conductor I44, electromagnet coil N3, conductors I43, conductor I42, back contact I H and conductor I29. When relay N3 is energized, contacts I50, I63 and 56 are closed on their front points and back contact I23 is opened. With the closing of front contact I50, relay N3 is established in the stick circuit comprising battery B4, conductor I46, contact I45 made on either its front or back point, conductor I44, contact I50, conductors I5I and I28 to the other pole of battery B4. Since 60 push key P6 is connected in parallel with back contact I4I its operation to close its contact will result in this circuit being established as just described. The same is true for back contact I52 which is also in parallel with back contact MI.

Circuit #33 (operation of selector L5) When the dispatchers selective equipment DSE (Fig. 8) is operated, coded impulses of current How over the dispatchers communicating circuit, conductors DI and D2 and conductors I58 and IGI, I60 and I51 to selector coil L5 which responds to close the contact I11, as will be later described. 7|

Circuit #43 (energizing of ofl and on relay When contact I11 of selector L5 is closed, the relay O8 is energized to an abnormal condition in a circuit comprising battery B5, conductor I34, electromagnet coil 05, conductor I18, contact I11 closed and conductors I18 and I15. The contact I11 is usually closed for only a short interval of time. Therefore, it is necessary that relay O5 is arranged to hold its contacts closed in the position to which operated until the electromagnet coil 08 is again energized, due to contact I11 again being closed when relay O5 is again operated to return its contacts to the other of the two positions.

Circuit #35 (connecting primary b of transformer M5 to dispatchers circuit when relay 05 is energized) When front contact I58 of relay O5 is closed, the primary coil b of transformer M5 is connected with conductors DI and D2 through the circuit comprising conductors I51, I80, and I14, front contact I50 closed, coil b and conductor I88.

Circuit #35a (connecting primary b of transformer M5 to dispatcher: circuit when relay N4 is energized) When front contact I58 of relay N4 is closed, the primary coil b of transformer M5 is connected with conductors DI and D2 through the circuit comprising conductor I51, closed front contact I58. coil b and conductor I58.

Circuit #36 (operation of selector L4) When the dispatchers selective equipment DSE (Fig. 8) is operated, coded impulses of current flow over the dispatchers communicating circuit, conductors DI and D2 and conductors I12, I18, HI and I81 to selector coil L4 which responds to close the contact I48, as will be later described.

Circuit #37 (energizing of "of and on relay 04) When contact I48 of selector L4 is closed, relay O4 is energized to an abnormal condition in a circuit comprising battery B4, conductor I48, electromagnet coil 04, conductor I41, contact I 48 and conductors I48, I88 and I29 to the other pole of battery B4. Since the contact I48 is usually closed for only a short interval of time, it is necessary that relay 04 be arranged to hold its contacts closed in the position to which operated until the electromagnet coil 04 is again energized due to contact I48 again being closed when relay O4 is again returned to the other of its two positions.

Circuit #38 (connecting primary b of transformer M4 to dispatchers circuit when relay O4 is energized) When front contact I89 of relay O4 is closed. the primary coil b of transformer M4 is connected with conductors DI and D2 through the circuit comprising conductors I81, HI, and I10, closed front contact I88, coil b and conductor I12.

Circuit #38a (connecting primary b of transformer M4 to dispatchers circuit when relay N3 is energized) When front contact I88 of relay N8 is closed, the primary coil b of transformer M4 is connected with conductors DI and D2 through the circuit comprising conductor I81, closed front contact I88, conductor I88, coil b and conductor I12.

INTERMEDIATE Cmonrrs Circuit #39 (normal intermediate circuit for block Q) This circuit, which is but partly shown comprises track rails AI and A2, including condensers K2 around insulated joints, condensers KI, conductor I19, front contact I80 and conductor I8I in the center of the main line track ML. The incompleted part of this circuit is similar to that shown at the right hand end of section E and section F of Fig. 1. Normally, the circuit is closed.

Circuit #40 (the intermediate circuit for main line track of stretch NOP combined with intermediate circuit ,for block Q, when relay T10 is de-energized) When contacts I80 and III of relay TIO are closed on their back points, conductor I8I is connected to conductor II2 through back contact I80 and conductor I18 is connected through back contact III with conductor IIO, thus connecting together the normal intermediate Circuits #26 and #39, forming one enlarged or combined intermediate circuit for the main line track of stretch NOP and the block Q.

Circuit #40a (intermediate circuit for main line 30 track of stretch NOP combined with intermediate circuit for block Q when relay O5 is energized) This circuit is the same as Circuit #40, except that, with contact II5 closed on its front point, coil 0 of transformer M5 is now inserted in the circuit.

Circuit #b (intermediate circuit for main line track of stretch NOP combined with the intermediate circuit for block Q, when relay N4 is energized) This circuit is the same as Circuit #40, except that with the closing of front contact I54, coil a of transformer M5 is connected in the Circuit #40 through conductor I55, front contact I54 and conductor I53. Back contact II3 being open, the circuit by way of contact H5 is open.

Circuit #41 (intermediate circuit for block Q and for passing siding track PS and main line track ML of stretch NOP combined as one circuit when track switch S5 is reversed and relay T10 is de-energized) When contacts I80 and III of relay TIO are closed on their back points, conductor I8I' is connected to conductor H2 and conductor I10 is connected with conductor IIO. With switch S5 reversed, contacts II8 and I01 are opened and contacts I28 and I21 are closed, hence conductor I08 is connected via contact I21 to the track rails AI and A2 of the passing siding track and conductor H1 is connected via contact I28 with conductor I08. Therefore, this combined intermediate circuit includes the intermediate circuit for the main line track ML connected in series with the intermediate circuit for the passing siding track PS.

Circuit #42 (intermediate circuit for block Q and intermediate circuits for passing siding track PS and main line ML of stretch N-()--P combined when track switch S6 is reversed) When contacts I80 and III of relay TIO are closed on their back points, conductor I8I' is connected to conductor H2 and conductor I19 is connected to conductor IIO. With switch S6 reversed, contacts I20 and I09 are opened and contacts I21 and I28 are closed; hence conductor H0 is connected via contact I28 with the track rails AI and A2 of the passing siding track and conductor I08 is connected via contact I21 with conductor I22. Therefore, this combined intermediate circuit includes the intermediate circuit for the main line ML connected in series with the intermediate circuit for the passing siding PS.

Circuit #42a (intermediate circuit for block Q, and for passing siding track PS and main line track ML of stretch N-OP when track switch S6 is reversed, relay T10 is tie-energized and relay N3 is energized) This circuit is the same as #42, except coil 0 of transformer M4 is inserted in the circuit through conductor I62, front contact I63 and conductor I65, and coil b is connected to the conductors DI and D2 through conductor I12, contact I66 and conductor I61.

Circuit #42b (intermediate circuit for block Q, and for passing siding track PS and main line track ML of stretch N--OP when track switch S6 is reversed, relay T9 is de-energized, relay T10 is tie-energized and relay N4 is energized) This circuit is the same as Circuit #42, except coil a of transformer M5 is inserted in the circuit through conductor I55, contact I54 and conductor I53 and coil b is connected to the conductors DI and D2 through conductor I58, contact I56 and conductor I51.

Circuit #420 (intermediate circuit for block Q and for passing siding track PS and main line track ML of stretch N-.-O-P when track switch S6 is reversed relay T10 is de-energized and relays N3 and N4 are energized) This circuit is the same as #42 except that with relays N3 and N4 both energized. There is a connection through both transformers M I and M5 with the dispatchers communicating circuit conductors DI and D2. This circuit is a combination of the circuit arrangement indicated for Circuits #42a and #421).

Circuit #43 (intermediate circuit for block Q and for passing siding track of stretch NO--P combined when both switches and S6 are reversed and relay T10 is tie-energized) When contacts I80 and III of relay TIO are closed on their back points, conductor I 8i is connected to conductor I I2 and conductor I19 is connected with conductor H0. This combined intermediate circuit includes the parallel connected track rails AI and A2 of .the main line in series with the parallel connected track rails AI and A2 of the passing siding as is described for Circuit #2913. The center of track conductors of both the main line and the passing siding are connected together to form a closed intermediate circuit, for both the main line and the passing siding of stretch NO-P which is in no way connected in the combined intermediate circuit for the stretch N-O-P and block Q when contacts I80 and II I are closed on their back points.

The block and intermediate circuit arrangement between passing siding locations, where the circuit arrangement at any one or more than one passing siding location is as illustrated in Fig. 3, is on the order of that shown between the location XI and X2 of Figs. 1 and 2.

The circuits above described are generally representative of, the arrangement of circuits for the equipping of the railway line in a dispatchers district. These circuits for any of the equipped tracks are arranged to function for trains operating in either direction or running forward or backward, and to always provide an intermediate circuit connecting together communication stations at different points on a train. The intermediate circuit for any stretch or block is normally electrically isolated from the intermediate circuit of any other stretch or block. Means are also provided for each intermediate circuit to be connected to the dispatchers communicating circuit, conductors DI and D2.

Before proceeding with a description of the operation of the system, the circuits and apparatus shown in Figs. 5 to 10, inclusive, will be described in detail.

Fig. 5 diagrammatically illustrates a track contactor, designed to operate when a train passes, which may be used to close the circuits of the controlling relays N to automatically connect intermediate circuits with the dispatchers communicating circuit, conductors DI and D2. For example, such a contactor may be used instead of the relay-T1, Fig. 3,'the contact I9I being substituted in the circuit for contact I4I so that conductor I92 replaces conductor I42 and conductor I93 is connected to conductor I29. A contactor of this description may be used at any point where relays are shown for the purpose of energizing the control relays N. In operation, the end of the lever I90, which is next to the track rail IAI is depressed by the tread of passing train wheels so that the outer end of the lever is elevated, closing the contact I9I. As is obvious, the lever I may be so located under the base of the rail IAI as to close the contact I9I when passing wheels deflect the rail IAI downward. Ordinarily, a mechanical contactor is less expensive for installation and operation than a track circuit and relay.

Fig. 6 is an elevation view of the arrangement of a train carried communication set with reference to the track rails and the wayside intermediate circuit system. Q6 diagrammatically represents the communication set or station on a train. This communication set shown in detail in Fig. 8 is in circuit with inductors U6, U1 and U8. The inductors U6, and U8 are located near the track rails AI and A2, respectively, and so as to be in inductive relation through an air gap with these track rails. Inductor U1 is located near conductor CON and in inductive relation therewith through an air gap. The'coils of inductors U6, U1, and U8 are connected in aiding relation, it being remembered that at any instant the flow of communicating current is in the same direction in track rails AI and A2 and in the opposite direction in the conductor CON.

Fig. '1 is a plan view of the arrangement of communicating sets at different points on trains relative to the intermediate circuit; for example, with one communicating set on the caboose CA and the other on the locomotive L0. The arrangement of each set, when viewed in elevation, is like that shown in Fig. 6. The details of the transmitting and receiving equipment are illustrated in Fig. 8. On transmitting a message from set Q1, inductors U9 and UII induce communicating electric currents, corresponding to the transmitted message, in the track rails AI and A2 to fiow in the same direction at any instant, while the inductor UI induces the communicating current into the conductor CON to fiow at the same said instant in a direction opposite to the flow of current in the two track rails. Since the conductor CON forms one side of the intermediate circuit and is connected at the ends of the block to the two track rails which function in parallel, forming the other side of the intermediate circuit, as heretofore explained, the communicating currents originating in the set Q1 flow in the intermediate circuit and are received by the inductors UI2, UI3 and UI4 from the track rail Al, the conductor CON and the track rail A2, respectively. These latter inductors are normally in circuit with the responsive device, such as a telephone receiver, which forms a part of the set Q8. Similarly, when set Q8 transmits, the receiver of Q1 is in circuit with the inductors so that the transmitted current, which is induced by the inductors into the track rails AI and A2 to flow therein in parallel and conductor CON to flow in the direction opposite to that of the current in the track rails, is reinduced into the inductors U9, UII, and UIO respectively and carried to the receiver, forming a part of the set Q'l. Thus, communication messages, such as telephone messages, may be transmitted back and forth between the two train points.

Fig.8 is a diagram of the details of the communicating sets carried on the train and in the wayside stations. That part of the diagram encompassed in the boundary line I, 2, 3, 4, comprises the selective and communicating equipment for the dispatchers station, represented by the symbol Q4 of Fig. 2, for which conductor 203 would be connected to conductor I00 and conductor 204 to conductor 89.

DSE is the dispatchers selective equipment, heretofore referred to, 01' the type similar to the Gill or the Western Electric systems in common use on the railroads for train dispatching and may be of the type used in telephone systems for selecting between subscribers. It is arranged so that coded impulses of electric current of different characteristics may be sent out over the dispatchers line, conductors DI and D2, from the dispatchers station. Located as may be required, along the railroad within the dispatchers district, are the selectors LI, L2, L3, etc., as heretofore explained. Each selector is responsive to close its contacts for one particular combination of impulses and not for any other combination of impulses. The dispatcher, desiring to operate selector LI, for example, sends out a code of current impulses to which this selector will respond, but to which selectors L2, L3, etc., will not respond to close their contacts. Selector LI, in responding, closes its contact 35 in circuit with of! and on" relay OI, the operation of which has been heretofore explained in Circuit #5.

Included within the boundary line, 2, 3, 4, 5, is illustrated the communicating set which may be used in the dispatchers ofiice, in connection with the selective equipment described, and which is also suitable for use with communication sets; such as Q1 and Q8, for a train and for the wayside communication stations Ql, Q2, Q3 and Q5. For train use, conductors 203 and 204 are connected, for example, to conductors I94 and I81 respectively for station Q1 and to con-' ductors I98 and 20I for station Q8. For the wayside stations, conductors 203 and 204 are connected respectively to conductors 95 and 86 for wayside station QI, conductors 95' and 35' for station Q2 and to conductors 91 and 88 for station Q3.

In the arrangement of the communicating set for station Q5 (Fig. 3) conductor 203 is connected to the switch CII and conductor 204 is 10 connected to the conductors I35 and I84. In this arrangement one communicating set is suitable to be used with either inductor set U4 or inductor set U5. In the event communicative relation of station Q5 with the intermediate circult for the main line (Circuits #26, #2611, and #26b) and the intermediate circuit for the passing siding (Circuits #27, #2711, and.#27b) is required at all times, one communication set may be connected directly with inductor set U4 and another communicating set with inductor set U5. As an alternative, receiver equipment may be normally in circuit with each inductor set and one transmitter equipment provided for connection to either as required. With either switch S5 or S5 open (reversed) so that the intermediate circuit for the main line is combined with the intermediate circuit for the passing siding (Circuits #28, #2811, #2817, and #280 and Circuits #29, #29a, #29b, and #290) both inductor 30 sets U4 and U5 are in inductive relation with the combined circuit. With both switches S5 and S8 open (reversed) the inductors a and c of both sets U4 and U5 are in inductive relation with the intermediate circuit (Circuit #293), which includes the track rails, and the inductors b of each set are in inductive relation with the intermediate circuit (Circuit #29A), which includes the center of track conductors.

The communication equipment in Fig. 8 comprises a receiver or loud speaker LS normally in circuit with a-transformer M1 by reason of the switch CI being maintained normally in position a by a spring or other device 2a. This circuit comprises conductors 220 and HI, amplifier AQ, conductor 2I8 containing the switch C5 and conductor 2I9, demodulator DEM, conductors 2H; and 2H, filter FR, conductor 2I5, switch CI in position a, conductor 2I3, coil 12 of transformer M1, conductor 2I4 and switch C3 in position a. It will be observed that the circuit arrangement for each communication station is normally for receiving messages. Also, forming a part of each communication set is a transmitter or other form of modulator TR of carrier current, an amplifer and generator of carrier current AM and a filter FT in a circuit adapted to be connected to coil b of transformer M1, the circuit including conductors 2M and 201 and conductors 2I3 and 2I2, which may be connected by switch CI in position b, conductors 208 and 2H connecting the filter FT with the amplifier and generator AM and conductors 209 and 2I0 connecting the transmitter TR with the generator and amplifier AM. The frequency of the carrier current used is high enough so that sufiicient energy will be transmitted across the air gaps between the train carried circuits and the intermediate circuit for efilcient and satisfactory service; yet, it is low enough so that the amount of energy transmitted to other wayside circuits, than those directly concerned in the communication operation, is so small as to produce little, if any detectable effect in such other circuits. The filters FT and FR are designed to pass electric currents of the desired carrier frequency,-

but to keep out currents of other frequencies.

Means are provided in Fig. 8 for simultaneous listening and transmitting, such as is practiced in commercial telephony. Switch C2 is normally in an open position a, but is adapted to be closed in positions b, c, and d. Switch C4 is in a circuit adapted to. connect an ear phone EP, or other similar instrument, to the main receiver circuit. Switches C2 and C4 may be combinedly connected to be operated to the various similar serted in the circuit to adjust the intensity of the response to the ear phone. The ear phone EP may be connected through conductor 222 to conductor 2|! and through conductor 221-, impedance and switch Cl .with conductor 2". With this arrangement, the station operator may talk .and listen at the same time.

If it is desired to leave the loud speaker L8 in circuit at the same Q time the ear phone EP is used, the intensity of the reception in the loud speaker LS may be adjusted by the switch C5 through the impedance connected with it. A switch C3 and adjustable impedance connected therewith is intended for adjusting the intensity of the reception in the loud speaker LS under normal conditions. It may also be used in diminishing the intensity of reception in them phones EP. Shouldamplification be desired for the signals to be received in the ear phones EP', it is obvious amplification may be added to the modulator DEM.

Fig. 9 comprises the same generalarrangement of circuits and receiving and transmitting apparatus ,as Fig. 8, excepting it provides for an audio'frequency'system instead of a carrier frequency system. The provision for simultaneous transmission and listening is practically identical with the arrangement described in Fig.8. One difference lies in the switch C8 being arranged only for connecting and disconnecting, the loud speaker ISI from the receiving circuit.

1 microphone. tted current.

TRI is an audio transmitter AMI is an amplifier for the .tr F1! is a filter, in the tra mitting circuit. FRI is a filter in the receiving circuit. ARI is a receiving amplifier. Ordinarily, the volume of current in the intermediate circuit, as transmitted from a wayside or train station, is of sufiicient intensity to be audible in an ear phone set. However, should this not be the case, amplification for the received signals may be combined in the circuit with filter FRI if desired. The filters Fri and FRI are designed to pass those currents of frequencies within the audio range, which are required for satisfactory service, and to impede current of frequencies outside which trains are involvedjthat communication may be carried on between'such stations at the v same time that communication is being carried on between the'dispatcher and trains and other stations over common circuits. Further, it is obvious that such stationsasql andQ2 maybe equipped with two communication sets each, one to operate on a predetermined carrier frequency, the same as that for the trains and the dispatcher, and the other on some other frequency, as the audio frequency. With'this arrangement, 5 when communication is desired with the trains, or with the dispatcher, or with the local stations. the conductors .203 and 204 will be connected with the conductors 95 and 96 respectively for local station QI and with the conductors II and 86' for the local station Q2. when communication between two stations like Q! and Q2 is desired through the use of the audio frequency set of Fig. 9, conductors 203 and 204' I will be connected with the conductors 95 and 15 96 respectively for local station Ql and with the conductors 95 and 86 for the local station Q2. Fig. 10 is a cross section. of a railway track showing the arrangement of sending and receiving coils or inductors with reference to the two go sides of the intermediate circuit for a wayside communication station Q9. This is the arrangement typical for the wayside stations Q3 and Q5 with some modifications for the latter as heretofore explained. For the local wayside stations 35 like Qi and Q2, the inductors Uli and U" are not necessary; only inductor UI6 would be required connected directly in circuit with the station Q9. As heretofore explained, the stations of which Q9 is representative, may be equipped .with communication sets operating on the frelarly equipped; but such communication could be carried on simultaneously with that being conductedbetween trains and the dispatcher, m the stations of which are operating on a differen frequency.

Operation The communication sets for trains and wayu side stations are referred to and described v under Figs. 8 and 9.

Figs; 6 and 7, alreadyreferred to and described, show the arrangement for co-operation between the train carried communication sets a and the wayside or intermediate circuits, in which the co-operation is inductive through an air gap between the wayside circuits and train carried circuits; there are no conductive co-opcrating features whatever between the train carried circuits and the wayside circuits.

Fig. 10 also heretofore referred to and described, indicates how local wayside stations are arranged in co-operative relation with the wayside circuits. a a While this invention is adapted for variouskinds of transmitted communications, for convenience I shall hereafter refer to it as a tclephone system in which speech is transmitted y from one communication station to another.

Assume that a train is in the block compris ing section A of Fig. 1, but not in the circuit for track relay TA, the train being equipped with transmitting and receiving telephone communication sets in the caboose and in the locomo- 1o tive. :The, intermediate circuit for this block has been heretofore described and designated as Circuit #1. Conversation maybe carried on 'between the caboose and-the locomotive via Circuit #1 while the train is within this block. 1

The normal condition of the circuits and apparatus for each communicating set is as indicated in Fig. 8. Assume that the conductor is to talk to the engineman. He will operate switch CI to the position b, thus connecting transmitter TR. with the coil b of transformer M1, the coil 0 of this transformer being connected to the train carried inductors such as U9, UIII, and UH of Fig. 7. The conductor talks into the transmitter TR. The speech current developed modulates the carrier frequency and is amplified. The filter F1 is designed to check the flow of current of other than the specified frequency; it passes the amplified modulated carrier frequency current which fiows through the transformer M1 and the inductors, causing a corresponding magnetic field for each coil or inductor U8, Ui I, and Ulfl which field intersects the track rails Al and A2 and the conductor I, respectively, causing a corresponding current to flow in the Circuit #1 heretofore described, of which the track rails and conductor I are a part. At the locomotive the train carried coils or inductors such as UI2,'UH, and Ui! of Fig. 7 intersect the magnetic field caused by the current flowing in the track rails Al and A2 and the conductor I; thus a corresponding current is induced in tha circuit of these inductors and flows through the transformer M1, the filter FR, which checks the how of electric current of frequencies other than the carrier frequency, the demodulator DEM and the amplifier AQ to the loud speaker LS where the voice currents are reproduced as speech. .As soon as the conductor has finished talking, switch CI of his set is restored to its normal position a. The engineman may change the switch Ci of his communication set to position b and reply to the conductor, the procedure in the operation being similar to that explained in the case of the conductor transmitting.

Should it be desirable for the engineman and the conductor to transmit and hear at. the same time, the switch C2 for each communicating set will be operated connecting conductor 2l2 with conductor M5 and switch C5 may be operated to position d, thus disconnecting the amplifier AQ and the loud speaker 18 from the circuit. coincidentally, with the operation of the switch C2 to the desired position, switch C4 may be operated to adjust the resistance or impedance in the circuit of the ear receiver EP so that the volume of sound received is of the proper intensity. With this arrangement, each party in talking may instantly break in on the other. Because of the necessity to get above train noises, the volume of sound given out by the loud speaker LS is far too great for reception in the usual ear phone. Therefore, the adjustable resistance of switch Cl is necessary. However, I may use an amplifier along with the demodulator, and adjust the volume of the output of same, in any case where the communication currents from a remote transmitting station received by the inductors of the train are not of suificient volume to be clearly and distinctly heard in the ear phones.

The switch C5 is provided not alone for opening the loud speaker circuit in case the output of the loud speaker should be found objectionable when receiving is desired through the ear phones. This switch C5 is also provided with adjustable resistance or impedance to change the volume of the reception in the loud speaker LS should this, at any time be desirable, whether the ear phones are being used or not. Switch C3 is provided for a purpose similar to that '01 switches C4 and C5. At the switch C3 the resistance is normally out of the circuit, but it may be inserted to reduce and adjust the volume of sound reproduced by either the loud speaker or the ear phones or both of them. With this arrangement, it is clear that the system of this invention may be used for simultaneous listening and transmitting.

Since the communication sets in the oiiice of the dispatcher and in the local wayside stations are of the same general character and arrangement as that for the train stations, the procedure by the attendants in these stations in the operation of the communication sets and in telephoning, including simultaneous speaking and listening, is the same as that explained in detail for the conductor and need not be repeated. v

Since block A is only partially shown in the diagram, Fig. 1, means for connecting the intermediate circuit for block A with the dispatchers communication circuit, conductors DI and D2 are not illustrated. In general, however, this means would be on the order of that illustrated and described for the location at section F, so that conversation may be carried on between the dispatcher and the train; and the general procedure in adapting the circuits for this conversation will be hereinafter described for the condition where the train occupies the stretch EF and is served by the intermediate circuit for that stretch.

When a train, which is moving toward the right in the diagram, passes into the circuit for relay TA, this relay is deenergized, shifting the contacts 2 and 8 to their back points, so that the intermediate circuits for the block which comprises section A and the stretch which comprises sections B, C, and D are now connected together as one circuit, heretofore referred to and described as Circuit #3. Although the train is moving, it will be observed that as it passes from one block to the one adjoining, the intermediate circuit relation with the train carried inductors is continuously maintained.

It has already been explained that inductor Ui is in inductive relation with conductor 5, and, therefore, with the intermediate circuit for stretch BCD, and is connected to the communication set for station Qi. Assuming that the communication set of Qi is of the same char acter as that on the trains and in the dispatchers offlce, conversation may now be carried on between the train and the local station QI, the procedure by the attendant in the local station being the same as that heretofore described for the conductor.

When the train passes into section B, track relay TB is de-energized, closing back contact 26. As the train is also in the section A, track relay TA being de-energized, back contact 21 is closed. Since back contacts 26 and 21 are now both closed, relay Ni is energized (Circuit #4) l and established in a stick circuit through its contact 3ia (Circuit #41!) resulting in the intermediate circuit arrangement heretofore 'described and referred to as intermediate Circuit #3b. Relay N i on becoming energized, closesf the front contacts I4 and 2|, thus connecting the transformer Ml with its secondary a in the combined intermediate circuit for the block comprising section A and the stretch BCD and its primary b to the dispatchers communicating center-of-track-inductor I circuit, conductors DI and D2. This places the train in position to communicate with the dispatcher in his station Q4. The procedure on the part of the dispatcher, in conversation with either the conductor or engineman or both on the train, is the same as that heretofore described for the conductor of the train. The communication impulses in a conversation between the train and the dispatcher pass by way of the combined intermediate Circuit #32), the transformer MI and conductors DI and D2. The conductor and engineman are now in conversational relation each through their respective train carried sets andintermediate Circuit #3b.

The attendant in the local station QI may still carry on conversation with the train and he may now also carry on conversation with the dispatcher, both via the intermediate Circuit #3b. It is also obvious that the conductor and engineman, or either of them, may join in a conversation with both the local station attendant and the dispatcher; in other words, all four parties are now on the line.

While the train is in the circuits for the two relays TA and TB, the three caboose station inductors U9, UI I, and UIII are in inductive relation with the track rails AI and A2 and the but since the intermediate circuit for the stretch B-CD does not include the track rails, only inductor UI3 of the locomotive set is active in transmitting and receiving from the intermediate circuit; 1. e., inductor UI3 is in inductive relation with conductor 5.

When the train has cleared the circuit for relay TA, this relay becomes energized and contacts 2, 6, and 21 are restored to their normal position, but relay NI remains energized because of the stick circuit established through its front contact 3Ia. The intermediate circuit is now that confined to the stretch BCD and heretofore referred to and described as Circuit #2b. As the track rails are not included in this intermediate circuit the co-operation for communication purposes is between inductors UID and UI3 on the train with the center-of-track-conductors 5 and I, it being assumed that the train is keeping to the main line. Conversation between the conductor and engineman on the train, the dispatcher and the attendant inthe local wayside station, or any two of them, may be continued via the intermediate Circuit #2b. The conversation between the train and the dispatcher having been concluded and the dispatcher not wishing to be bothered with any conversation there may be between the conductor and engineman of the train, or between the train and the local station, may annul the connection of the intermediate Circuit #21; to the conductors DI and D2 by operating the selector LI to energize the relay OI to shift the contacts 23, I2 and I8 to their front contact position, after i which he may again operate selector LI to return the contacts to their normal position. The interval of time elapsing between the breaking of back contact 23 and the making of front contact 23 or vice versa, is sufiicient to break the circuit of relay NI to cause this relay to become de-energized, restoring contacts 3Ia, I4, I0, and 2I to their normal position and re-establishing intermediate Circuit #2.

During the time that the train is in the stretch B C-D, and whether intermediate Circuit #2 or #2b is established, the two train carried sets are in continuous communicative relation with each other and with the set of local station QI so that conversation may be carried on at will between the conductor and engineman or between either or both and the attendant in the local station.

Should the track switch SI have been operated by the device RI for the train to take the siding, conversation between the conductor and engineman may be carried on continuously if desired since the intermediate Circuits #3, #3a and 1 #3b, #2, #2a and#2b serve both the main line and the passing siding. Conversation between the dispatcher and the train may be carried on while the train is entering the siding, similarly as has been heretofore explained with the train 14 keeping to the main line. Also, conversation may be a four-party affair by way of the intermediate Circuits #3b, #2b and the Circuit #7a and conductors DI and D2, between the dispatcher in station Q4, the local station QI and go the conductor and engineman on the train.

As soon as the rear end of the train which is entering the siding has cleared the circuit for the relay TA, the dispatcher may operate the selector LI to close the contact 35 to energize the 25 relay OI in Circuit #5 to shift its contacts 23, I2, and I8 to their front points; thus, through the opening of contact 23, de-ener'gizing relay NI causing front contacts 3Ia, I4, and 2I to open and back contact III to close. At this point, :0 intermediate Circuit #2a is established; but this may be changed, entirely separating the intermediate circuit from the wayside communication circuit, conductors DI and D2, by the dispatcher again operating selector LI causing relay OI to 35 energize to shift its contacts 23, I2 and I8 to their back points and normal condition.

The dispatcher having annulled the connection of the intermediate Circuit #21) through coils a and b of transformer MI to the dispatch- 40 ers circuit, conductors DI and D2, heretofore described may establish the intermediate Circuit #2a by the operation of the selector LI to energize the "off and on relay OI in the Circuit #5 to close its contacts 23, I2, and I8 on their front 15 points. This operation closes the front contacts 23, I2, and I8 and connects secondary c of transfonner MI in the intermediate circuit and the primary b to the conductors DI and D2 (Circuit #7). By this means, the dispatcher may carry 50 on conversation with the conductor or engineman, or both on a train on the main line or on the passing siding track, or with the local station QI whether a train is within the stretch B-C-D or not. 55

A train TA4 is hown "on the passing siding track at location XI of Fig. 1. The attendants on the train, which I have assumed to be moving over the railway, may carry on conversation with the attendants on the train TAI while 60 this latter is in the track circuit section for relay TA of block A via intermediate Circuits #3, #3a or #312; while in the stretch B-CD via the intermediate Circuits #2, #2a or 2b; and while in the track circuit section for relay TE 55 via intermediate Circuits #9, #911, #9b or #9q. Also, under the same conditions, both of these trains, or either of them, may carry on conversation with the local station QI, and with the dispatcher via intermediate Circuits #3a, #3b, #2a, #22), #911, #91), and #90.

Normally, the station QI is not in communicative relation with the dispatcher, but such relationship may be established, initiated by the at- 7 tendant in station QI, by the closure of the contact of push key P2 which energizes relay NI in Circuit #411. This establishes the intermediate Circuit #2b connected via transformer MI and Circuit #7a to conductors DI and D2 and thus to dispatchers communication set in station Q4. The procedure in conversation is the same as heretofore explained. When the conversation is finished, the dispatcher may annul the connection of transformer MI with conductors DI and D2 in the same manner as heretofore explained.

A train moving toward the right still in passing from either the main line track or the siding track of the passing siding location XI enters first the circuit for relay TD, closing back contact 2|, and then the circuit for relay TE, thus shifting the contacts 42, 8, and 22 to their back points. With contacts 42 and 8 closed on their back points, the intermediate circuits normally existing for stretches B-C-D and E-F are now combined as one circuit heretofore referred to' and described as Circuit #9. Communication between the conductor and engineman of the train and the attendant at station QI may be carried on at will and continuously, if desired while the train is making this movement.

Since contacts 3| and 22 are closed, relay NI is again energized, inserting secondary a of transformer MI in the combined intermediate Circuit #9, establishing the Circuit #91), and the primary b is connected across the conductors DI and D2, as referred to in Circuit #71:. Thus, the circuit system is arranged for the train to initiate communication with the dispatcher for announcing its departure from the passing siding location XI and for any other communication which may be desired between the dispatcher and the train. During this interval local station QI being in communicative relationship through inductor UI with the combined intermediate Circuit #9b may carry on conversation with the train and with the dispatcher.

As soon as the train has cleared the circuit of relay TD, the dispatcher may then, or thereafter, disconnect the combined intermediate circuit for the stretches B-C-D and E-F (Circuit #91:) or the individual circuit for stretch B-G-D (Circuit #2) from his communication circuit, conductors DI and D2, by operating the selector LI and consequently, the relay OI as heretofore described.

It will be observed that the annulling of the connection established by the relay NI of the intermediate circuit for stretch B--CD with the dispatchers communication circuit, that is, the changing of the intermediate Circuit #2b back to intermediate Circuit #2, cannot be accomplished so long as a train occupies both of the two track circuits for relays TA and TB or both of the two track circuits for relays TD and TE. The dispatcher can annul the connection, after the same has been established, whenever a train traveling in either direction has cleared the insulated Joints between the sections A and B and sections D and E.

When the train proceeding toward the right has cleared the track circuit of relay TE, the normal intermediate Circuit #8 for the stretch EF is restored. Communication between conductor and engineman of the train may be carried on via Circuit #8, in a manner similar to that heretofore described for other blocks. Assume that the dispatcher desires conversation with the train in the stretch E-F. He will operatehis selective equipment DBE to send out a code of impulses over the circuit including coilductors DI and D2 to which selector L2 will respond and none other. This will cause contact 38a to close, energizing "ofl and on relay O2 in Circuit #I2 to close its contacts 38, 52, and 48 on their front points. The closing of contact 46 connects primary b of transformer M2 via Circuit #14 directly to the dispatchers communication circuit, conductors DI and D2. The closing of front contact 88 inserts secondary m coil c of transformer M2 in the intermediate circuit for the stretch E-F, establishing Circuit #8a. The closing of front contact 52 inserts the secondary a of transformer M2 in the intermediate circuit for the'block G establishing Circuit 15 #100. It will be noted that with this arrangement, when the dispatcher operates selector L2 he connects the two intermediate circuits, that for stretch E-F (Circuit #8) and that for block G (Circuit #10) to his communication circuit 20 conductors DI and D2. Conversation between the conductor and engineman of the train and the dispatcher may now be carried on via the communication circuit conductors DI and D2, transformer M2 and intermediate Circuit #84. gg When through with the conversation, the dispatcher may disconnect his communication circuit conductors DI and D2 from the intermediate Circuits #80 and #100 by the operation of the selector L2 and consequently, relay 02. This re-establishes intermediate Circuit #8 for stretch 15-! and intermediate Circuit #10 for block-G. when the train passes into the section F, relay TF is'energized, due to the wheels and axles across rails AI and A2, closing contacts 54, 40, and BI 5 on their front points so that the intermediate circuits for the stretches E-F and G are new combined as one circuit, #11. Conversation between the conductor and engineman of the train may now be carried on via intermediate Circuit #11. Should the dispatcher wish to communicate with the train at this time, he will operate the selector L2 to insert the coils a and c of transformer M2 in the intermediate Circuit #11 and connect coil 11 to the conductors DI and D2, 5 as heretofore explained, thus establishing intermediate Circuit #11a. The closing of front contact 5| shunts secondary a of transformer M2 so that only secondary coil c remains in the combined intermediate Circuit #ila, thus lowermg the impedance of the circuit. The dispatcher may now carry on conversation with the train through combined intermediate Circuit #11a and primary b of transformer M2. This may be con-,-

tinued as long as the train is within the section F and until the relay O2 is again operated to restore its contacts, 52, and 44 to their normal condition. Conversation between the conductor and engineman at this time will be via combined intermediate Circuit #lla. I so When the train has cleared thetracksection F, relay. TF becomes de-ener'gized and the contacts 54, 40, and BI are returned to their normal position. The combined Circuit #11:: is'abol ished and Circuit #10a is re-establisbed and 55 now functions for conversation between the conductor and engineman, and between the dispatcher and the train, since the contacts 2!, 52,

and 46 still remain on their front points. Should the dispatcher cancel the connection of the in 'termediate circuit for block G with his com-' munication circuit, conductors DI and D2, by the operation of selector L2, contact 52 would be made on its back point, thus re-establishing intermediate Circuit #10. Conversation between the conductor and engineman of the train would now be through this circuit.

The train continues into the circuit of relay TG, ale-energizing this relay and causing contacts 56, 60, and BI to be made on their back points, thus connecting together as one combined Circuit #17 the normal circuits for block G and stretch HIJ. During the period that the train is in the circuit for relay TG, conversation may be carried on between the conductor and engineman via Circuit #17.

Should the dispatcher desire to communicate with the train while it occupies the track circuit for relay TG, he will operate selector L3 to establish Circuit #17a connected to his wayside communication circuit, conductors DI and D2. Conversation between the conductor and engineman and the dispatcher will now be by way of intermediate Circuit #l7a, transformer M3 and wayside communication circuit, conductors DI and D2. When the conversation is concluded, the dispatcher may disconnect combined intermediate Circuit #17a for block G and stretch H-IJ from conductors DI and D2 by the operation of selector L3 to restore contact 66 to its back point, thus re-establishing intermediate Circuit #17.

It should be noted here that the dispatcher may also carry on conversation with the train while it is in the track circuit for relay TG, by closing the contacts 52 and 46 of relay 02 on their front points by the operation of selector L2, thus establishing intermediate Circuit #170.

While the train is in the section for relay TG, conversation may be carried on between the train and the local station Q2 via the combined intermediate Circuits #17, #l'lai, #1722 or #170 and U2. When the train enters the circuit for relay TH, but is still in the circuit for relay TG, back contacts and 8| are closed, energizing relay N2 in the Circuits #18 and #19 to close its contacts 8511, 6.8, and 15 on their front points and to break the contact 64 from its back point. This automatically connects the comfined intermediate circuit for block G and stretch HI-J, Circuit #l'Zb, with the dispatchers communicating circuit, conductors DI and D2. via primary b and secondary a of transformer M3. The train attendants are now in position to announce to the dispatcher the arrival of the train at passing siding location X2, and conversation between the train attendants and dispatcher maybe carried on. Also, the train attendants may have conversation with the local station Q2, and this latter with the dispatcher.

As the train clears the circuit for relay TG, this relay becomes energized, restoring the individual intermediate circuits for block G and stretch H--IJ, #10 and #16. The train conductor and engineman may still carry on conversation between themselves and with the dispa cher and with the local station Q2 and the latter and the dispatcher may talk together.

The dispatcher may now annul the connection of the intermediate Circuit #16 for the stretch I-lI--J, with his communicating circuit conductors DI and D2 by operating selective equipment DSE to send out the code of current impulses to which selector L3 will respond, closing its contact 89. This energizes relay O3 to shift its contacts 11, 66, and I2 to their front point; thus relay N2 is de-energized and. coils a and b of transformer M3 are disconnected from the intermediate Circuit #16 for stretch H-I--J and from the communicating circuit conductors DI,

and D2 respectively. However, when relay O3 is energized to shift its contacts to their front points, coil 1) of transformer M3 is connected to conductors DI and D2 through contact I2 and coil 0 of transformer M3 is inserted in circuit with intermediate Circuit #15, establishing intermediate Circuit #15a, so that conversation between the train stations, the dispatcher and the train and the local station Q2 may be continued. But, if selector L3 is again operated to energize relay 03, contacts 71, 66 and I2 are shifted to their normal condition, back points; primary 1) of transformer M3 is disconnected fromthe conductors DI and D2 and secondary coil 0 is shifted out of the intermediate circuit for H-I-J. Intermediate Circuit #15 is reestablished for stretch HI-J. Conversation may still be continued between the conductor and engineman on the train and between either or both of them on the train and the local station Q2. The procedure in carrying on conversation between the conductor and engineman on the train and between the local station Q2 and the train attendants when at passing siding location X2 is similar to that already described for the passing siding location XI. Also, the operation of the circuits for the various positions of the train for conversation with the dispatcher is similar to that described for passing siding location XI.

Intermediate circuit #24 for the block K has been heretofore described. Within this block is a local wayside station Q3 associated with the intermediate Circuit #24 through coils a and c of inductor set U3 being in inductive relation with track rails AI and A2 respectively and coil 1) being in inductive relation with conductor 94. Localstation Q3 is always in communicative relation with a train in block K, and with the train when it approaches or leaves block K so that the intermediate circuit for block K is combined with the intermediate circuit for the adjoining stretch as the stretch HI-J. The intermediate circuit for the stretch HIJ combined with the intermediate circuit for the block K is Circuit-#240, heretofore described. Assuming that the block K is provided with a circuit organization the same as that controlled by the selector L2, the dispatcher may confer with the attendant in the local station Q3 by operating the selector to connect the intermediate Circuit #24 or an enlarged intermediate circuit as #24a with the communication circuit conductors DI and D2. It is also obvious that when the train is in the track circuit section for relay TK, that communication; between the dispatcher and the attendant in station Q3 may be carried on by way of the intermediate Circuit #2411, transformer M3 and conductors DI and D2.

Let it be assumed that two wayside local stations, for example, local stations QI and Q2 are each equipped with a communication set operating on. a frequency different from that used on the trains and in the dispatchers office, and that these two local stations desire to converse at the same time that the conductor and engineman of train TA2 wish to talk with each other. Push keys P2 and P5 of'stations QI and Q2, respectively, are operated to connect the.

intermediate Circuits #2 and #15, for stretches B-C-D and H-I J, respectively, through the respective transformers MI and M3 with the wayside communication circuit conductors DI; and D2. Conversations may now be carried on Cir at the same time, in a manner as heretofore described, between the attendants at the stations QI and Q2 and between the conductor and engineman of train TA2. As the communication signals are carried on different frequencies, there will be no interference of one set of conversations with the other. It is also evident, that at the same time that conversation is under way between the attendants of stations QI and Q2, the dispatcher may talk with train TA2, or TAI or TA I; or he may operate the selector L2 controlling transformer M2 and talk to trains TA3 and TA coincidentally with the attendants in local stations QI and Q2 talking with each other. In each of the examples mentioned, a plurality of conversations may be transmitted simultaneously over circuits which are common to both sets of communications. The stations QI and Q2 may be equipped with a plurality of communication sets, one set on a frequency for communication with the trains and the dispatcher and the other set on a different frequency for communication between the attendants in the two stations. Simultaneous speaking and listening may be indulged in, for the stations concemed with each set of communications, in a manner heretofore explained. I have shown two trains passing each other at location XI. Train TA4 is on the passing siding track and train TAI is on the main line track. These trains may communicate with each other and the local station QI via the intermediate Circuit #2. The dispatcher may have conversation with the local station QI and either or both trains by way of intermediate Circuit #2a, transformer MI and conductors DI and D2.

Other than the trains TA and TAI in stretch BCD, I have shown train TA3 in stretch E-F, train TA5 in block G and train TA2 in block X2. Since the intermediate circuits for these blocks are electrically isolated from each other, communication cannot normally be carried on between the trains, except trains TAI and TA4. Excepting for the last two mentioned trains, conversations may be carried on simultaneously between the conductor and engineman on each train, without the conversation for any one train being heard by, or interfering with the conversation of, any other train. Train TA2 may have conversation with local station Q2 and normally, this conversation will be exclusive to the train and station Q2 and independent of that with and on other trains.

The dispatcher, after operating the selector associated with any intermediate circuit, may have conversation with any communication station associated with that circuit; for example, by operating the selector LI, the dispatcher may have conversation with any one or all of the stations on trains TAI and TA4 and with local station QI, and this conversation is exclusive to the stations mentioned. Similarly, the dispatcher may have conversation with trains TA3 and TAB through the coils a and 0 respectively of the transformer M2, and this conversation will be exclusive to the two trains and the dispatcher. Other communication stations, where two or more are associated with the same intermediate circuit, may carry on communication between themselves at the same timethe dispatcher is talking with trains TA3 and TAl. Other examples may be cited, as is evident, to show the flexibility and high degree of utility of the system embodied in this invention.

Referring to the method of connecting the intermediate circuits with the dispatchers communication circuit, conductors DI and D2. as illustrated for stretch E-F and "block G, it is evident that by omitting the coil a of transformer M2 and the connections thereto through the contact 52 of relay 02, that only the intermediate circuit for stretch E-F will be connected to the conductors DI and D2 whenselector L2 is operated. Such a circuit organization may also be provided for the block G, in which event the dispatcher may have exclusive conversation with either train TA3 or TA5. I have illustrated the method for connecting the two intermediate circuits for stretch E--F and block G to the conductors DI and D2 at the same time primarily for the reasons of economy, and convenience for the dispatcher. For railway lines of light and moderate trafiic, and especially single track lines, there would seldom be more than one train between passing siding locations XI and X2 at any one time.

It is obvious I have provided a communication system in which each train is normally in a communication zone of its own, which, in effect, travels with the train and to which communications of the train are restricted. In it are, incorporated provisions harmonizing with the general method of operating trains on a modern railway.

In the operation of trains over the railway line equipped as indicated in Fig. 3, both sides of the intermediate circuits are in inductive relation with the inductors on the train and the inductors for the local wayside station, the track rails connected in parallel forming one side of the intermediate circuit and the conductor in the center of the track, the other side of the intermediate circuit.

With a train in the track circuit for relay T5, the relay contacts I82 and I05 are made on their back points, thus establishing the intermediate Circuit #30. Electric current impulses for conversation between the conductor in the caboose and the engineman in the cab of the locomotive are transmitted through intermediate Circuit #30. Also, voice currents passing between a train station and the local wayside station Q5 flow in intermediate Circuit #30 and through inductor U5. Should the dispatcher desire conversation with the train at this time, he will operate selector L5 to cause the closing of front contacts H5 and I59, thus establishing intermediate Circuit #30 in circuit relationship with conductors DI and D2 through the coils b and c of transformer M5. Over this channel conversation may be carried on between the conductor and engineman of the train, the attendant in local wayside station Q5 and the dispatcher.

When the train enters section N, relay T6 de-energizes closing contact I30, thus energizing relay N4 in Circuit #31 to close front contacts I 31, I54 and I56 on their front points to connect coils a and b of transformer M5 in intermediate Circuit #30 and to conductors DI and D2 respectively. Back contact H3 being opened when relay N4 is energized, coil c of transformer M5, if still in Circuit #30, is eliminated from the circuit. The conductor and engineman on the train may talk to each other and may initiate and carry on conversation with the dispatcher. Station Q5, being inductively connected to intermediate Circuit #30, may have conversation with both the train attendants and the dispatcher.

When the train clears track circuit section of relay T5, intermediate Circuit #30 is automati- 

